Trading is good to increase own resources (I almost never trade 1:1, mostly 1:2, depending on how badly the other person needs my resources) or doing the invers

Trading is good to increase own resources (I almost never trade 1:1, mostly 1:2, depending on how badly the other person needs my resources) or doing the inverse: getting down to 7 resources during another player's turn to prevent having to dump half of it if a 7 is rolled.